User blog comment:Super29392/Theories on the upcoming update/@comment-31221741-20180114083107/@comment-27248965-20180114084432

There are mushrooms in Fluoruma, and even the sneak peek photo for Fluoruma City by Lando showed the mushrooms, so even though Poison was a popular guess, Grass was still one of the possible types. A better example would be Frostveil, where everyone guessed Ice, but it turned out to be Dark.

Anyway, we have narrowed down to 6 possible final Gym types: Poison, Psychic, Ghost, Normal, Rock and Steel. We should only step in if there are unreasonable guesses, such as Dragon.